According to the current prior art, helicopters reach top speeds of up to a maximum approx. 360 km/h. The rotor drive axis, about which the rotor blades rotate, always coincides here with the rotor bearing axis, about which the rotor blade shafts are fastened. Said rotor bearing axis is formed mechanically by the rotor shaft. During hovering flight, all of the points on all of the rotor blades of a rotor that are equally far away from the rotor drive axis have, given an identical angular speed (dimension Z−1), the same rotational speed (dimension L×Z−1), i.e. cover distances of equal length at the same time. Points in the vicinity of the rotor drive axis have a lower rotational speed here than points further away therefrom. If the helicopter moves forwards with a certain translational speed, the rotational speed of the rotor blades is superimposed on the translational speed of the helicopter.
In the following, a rotor system is referred to as “anticlockwise” in which its rotor blades rotate anticlockwise in a top view of the helicopter. The following directional details always refer to a top view of the helicopter from above, with the front oriented upwards in the plane of the drawing. The rotational phase of a rotor blade indicates the current position in relation to the axis of rotation of the rotor.
In the case of an anticlockwise rotor system, the translational speed of the helicopter itself is added to the rotational speed of the rotor blade on the right side, while the translational speed is subtracted from the rotational speed of the rotor blade on account of the opposed movement of the rotor blade in order in each case to obtain the speeds of the respective rotor blade above ground. The different effect of the translational speed of the helicopter on the speeds of the rotor blades above ground depending on the rotational phase thereof gives rise to a speed profile of the rotor blades in accordance with their position. In the case of an anticlockwise rotor system, the maximum of said profile is located on the right side and the minimum on the left side. The differences therebetween is all the more greater, the greater the translational speed of the helicopter. When the rotors are on the right side, a higher air resistance therefore prevails, whereas the air resistance is lower on the left side. This results in a correspondingly different air resistance on the right and left side. Both effects can be compensated for via a change in the angle of inclination of the rotor blades in relation to the horizontal until the air flow stalls because of too great an air resistance at a speed which is (too) high. This is the limiting factor for achieving higher translational speeds.